The present invention relates generally to integrated circuits (ICs) and more specifically to IC packages with on-package decoupling (OPD) capacitors.
Decoupling capacitors or chip capacitors are typically used to remove unwanted signals or reduce power supply noise to the chip. During normal operations of the IC, power usage of the chip may vary. For example, the chip may try to draw additional current from the power supply when there is a change in the state of the circuit. The constant change in the current consumption of the IC causes current fluctuation and creates unwanted noise in the chip. As such, decoupling capacitors are usually included in a typical IC package to stabilize the current fluctuation in order to make the device run more smoothly.
These capacitors are usually placed on the substrate layer of the IC package. However, they cannot be placed too close to the die and there must be ample space between the die and the chip capacitors surrounding the die. Hence, when a bigger die is used, a bigger substrate is needed to accommodate the chip capacitors. In other words, a bigger die would require an even bigger packaging substrate in order to fit the die and all the chip capacitors in the IC package. The increase in package size not only increases packaging cost but also manufacturing risks due to the larger packaging substrate used.
Thus, it is highly desirable to have an IC package that can accommodate all the chip capacitors that need to be placed in the IC package without further expanding the size of the packaging substrate.